Aircraft flight decks have become increasingly sophisticated and rely to a large extent on technology and automated controls that have significantly reduced pilot workload and enhanced systems reliability and efficiency and, as such, passenger safety. In addition to advanced navigation capabilities provided by, for example, GPS and graphical displays that contribute to greatly improve situational and operational status awareness, advances in autopilot systems have proven of tremendous assistance to pilots in maintaining both aircraft control and the smooth and efficient operation of those aircraft that are provided with such capabilities.
Autopilot systems provide functions that range from, at the lowest end of the range of capabilities, simple wing leveling to, in more advanced systems, aircraft directional and course control to maintain and track a selected course, altitude maintenance and adjustment control, and adjustments to the aircraft throttle(s) to maintain and effect desired changes in aircraft velocity.
Automated control of the aircraft throttle(s), in particular, presents special problems that have, in the past, limited such capabilities to only the largest or, at least, the most technologically complex and advanced aircraft, such as large commercial airline passenger jets, advanced regional and general aviation jets, and high-end turbine propeller airplanes. Such autothrottles provide the ability to realize truly automated, hands-off control of the aircraft, thus providing increased aircraft operating efficiencies, reducing cost in, for example, the consumption of fuel, and vastly decreasing pilot workload and thereby notably increasing flight safety. But providing autothrottle capabilities in an aircraft requires, with the technologies currently in use, physical, spatial and mechanical accommodations that limit this functionality to only the largest and/or most technologically advanced aircraft which, in most cases, must be designed and constructed to include and utilize autothrottle functionality.
In most aircraft, the throttle(s)—which are selectively adjustable to cause the engine(s) to generate a predetermined amount of power or thrust to propel the aircraft at a desired velocity—are adjusted by pilot-controlled manual override displacement of one or more graspable handles on levers that are pivotally mounted for rotation through a limited arc in a throttle quadrant in the aircraft cockpit or flight control deck. These levers are typically connected to the engines or engine controllers by control cables that are longitudinally displaced as the positions of the throttle levers are pivotally adjusted.
In almost any aircraft, not insignificant forces must be applied to the throttle levers—whether manually by a pilot or by an operating motor of an autothrottle system—to vary or adjust the pivoted positions of the levers. The motors of the system, therefore, must be fairly robust, both in size and weight (to provide sufficient torque and operating forces applied to the throttle lever) and in construction (to assure continued reliability through tens of thousands of activations and operations). As a consequence, only aircraft specifically designed and constructed with sufficient clearances and space to accommodate these motors and associated elements at, in and/or alongside the throttles quadrant of the cockpit, and capable of accepting the significant additional weight associated with these systems and their component parts, are able to incorporate such autothrottles into and with their flight controls. There is moreover virtually no ability to retrofit or add autothrottle capabilities into existing aircraft that have not already been specially designed and constructed to accommodate the associated operating components of an autothrottle system.
It is in addition important, to assure safe operation of the aircraft under continued control by the pilot, that the pilot can quickly and easily override or otherwise assume manual control of the throttles from an activated autothrottle system in the event that operating conditions in the aircraft may suddenly require that the pilot assume immediate physical control of the throttles, as in an emergency or any circumstance in which the pilot deems it appropriate, without having to first manually disengage the autopilot or autothrottle system(s). Such circumstances, however may have a detrimental result in that sudden pilot engagement may cause operations of the aircraft throttle control outside of a desired throttle range. Such an occurrence can lead to slow engine responses or even a stalling condition at a worst case scenario. Accordingly, an improved autothrottle is beneficial to deter or prevent pilot operation of an autothrottle outside of a desired operating range.